Tensio-active glucoside urethanes

ABSTRACT

The invention concerns the use as surface-active agent of a glucoside alkyl urethane (I) which is composed of units of the general formula (II): A(O—CO—NH—R) s  wherein A represents a glucosyl unit of a starch hydrolysate molecule, the starch hydrolysate having a Dextrose Equivalent (D.E.) ranging from 1 to 47, (O—CO—NH—R) represents an N-alkyl aminocarbonyloxy group replacing a hydroxyl group of the glucosyl unit A, and wherein R represents a linear or branched, saturated or unsaturated alkyl group containing from 3 to 22 carbon atoms, and s represents the number of alkyl carbamate groups per glucosyl unit which number is expressed as degree of substitution (DS) with said DS value ranging from about 0.01 to about 2.0. The invention further relates to novel glucoside alkyl urethanes (I), and a method for their manufacture and to compositions containing one or more of glucoside alkyl urethanes (I). The glucoside alkyl urethanes (I) have good to excellent tensio-active properties in combination with good biodegrability and they are suitable as surfactants for use in household and industrial applications, e.g. as detergents, emulsifiers, emulsion stabilisers, foaming agents, foam stabilisers, dispersants and wetting agents.

FIELD OF THE INVENTION

[0001] This invention relates to glucoside urethanes, in particular tothe use as surfactant of alkyl urethanes of glucosides, to noveltensio-active glycoside alkyl urethanes, to a process for theirmanufacture and to compositions comprising said urethanes.

BACKGROUND AND PRIOR ART

[0002] Tensio-active agents are widely used as surfactants incompositions for household and industrial applications in which they mayact as detergents, foaming agents, foam stabilisers, wetting agents,emulsifiers and/or emulsion stabilisers.

[0003] The oldest type of tensio-active agents are the alkali soaps offatty acids. They were mainly used as detergents and are still widelyused today in spite of their relatively weak tensio-active properties.Much stronger synthetic surfactants have been developed since. The eldergeneration of widely used synthetic surfactants was mainly formed ofalkyl benzene sulfonates (ABS). However, ABS, in particular branchedalkyl benzene sulfonates, presented the disadvantage to cause seriouswater pollution problems due to their poor biodegradability.Accordingly, ABS have been largely replaced by linear alkyl sulfonates(LAS) with ten or more carbon atoms in the alkyl chain and which presentimproved biodegradability compared to ABS surfactants.

[0004] In the search for alternative or improved surfactants, alsomonomeric and dimeric sugars such as glucose and sucrose (saccharose)have been used as starting material for the synthesis of non-ionicderivatives with tensio-active properties.

[0005] V. Maunier et al. (Carbohydrate Research, 299, 49-57, (1997))disclosed tensio-active properties of several 6-aminocarbonylderivatives of methyl α-D-glucopyranoside and D-glucose and comparedthem with the properties of the urethane methyl6-O-(N-heptylcarbamoyl)-α-D-gluco-pyranoside.

[0006] The synthesis of several sucrose N-n-alkyl urethanes and theirtensio-active properties have been disclosed i.a. by H. Bertsch et al.(J. prakt. Chem., 11, 108 (1960)) and by W. Gerhardt (Abh. Dtsch. Akad.Wiss. Berlin, Kl. Chem., Geol. Biol., Vol 1966 (6), 24-32, (1967)). Theurethanes are prepared by reacting sucrose with the correspondingn-alkyl isocyanate (H. Bertsch et al. o.c.) and by reacting sucrose withpotassium cyanate in the presence of a selected n-alkyl halogenide indimethyl formamide (W. Gerhardt, o.c.). The derivatives present moderateto good tensio-active properties but only at rather high concentrationand the sucrose n-alkyl urethane derivatives with long alkyl chainssuffer from poor solubility in water.

[0007] To overcome the poor solubility in water of the monomeric anddimeric sugar n-alkyl urethanes, several approaches were examined,including the synthesis of n-alkyl urethanes of ethoxylated orpropoxylated monomeric and dimeric sugars and the synthesis ofalkoxylated alkyl urethanes of monomeric and dimeric sugars. Thesynthesis and tensio-active properties of n-alkyl urethanes derived fromethoxylated and propoxylated sucrose, respectively mannitol, have beendisclosed by W. Gerhardt (o.c. and German Patent DE 1 518 696). Thesynthesis and tensio-active properties of 1-(n-alkyloxy)-ethylurethanesof sucrose have been disclosed by T. Lesiak et al. (J. prakt. Chem., 319(5), 727-731, (1977)).

[0008] Moreover, the preparation of miscellaneous urethanes derived fromvarious carbohydrates have been disclosed.

[0009] I. Wolff et al. (J. Am. Chem. Soc., 76, 757 (1954)) mentioned tohave prepared urethanes of starch, but later studies by E. Asveld et al.(Carbohydrate Polymers, 4, 103-110, (1984)) revealed that in the aqueousreaction conditions used by I. Wolff et al. no urethanes but onlymixtures of the carbohydrate and urea compounds were formed.

[0010] European patent application EP 0 801 077 discloses n-(C₁-C₁₈)alkyl urethanes of cellulose and alkoxylated cellulose. Similarly,German patent application DE 43 38 152 A1 discloses n-alkyl urethanes ofstarch and partially acetylated starch. Both patent applicationsdisclose the use of the alkyl urethanes as thermoplastic material butare completely silent about possible tensio-active properties of saidurethanes.

[0011] European patent application EP 0 157 365 discloses variousurethane derivatives of polysaccharides including alkyl carbamates ofcellulose, amylose, chitosan, dextran, xylan and inulin, and disclosestheir use for the optical resolution of racemic mixtures. No mention ismade of possible tensio-active properties of the carbamates.

[0012] In co-pending European patent application EP 98870135.5(applicant: Tiense Suikerraffinaderij n.v.), tensio-active alkylurethanes of fructans, particularly of inulin, are described.

[0013] In view of the steadily increasing demand for surfactants and theincreasing severity of national and supra-national Regulations withrespect to toxicity and biodegradability of surfactants for householdand industrial use, the search for alternative and for more efficientand/or better biodegradable surfactants is continually going on.

OBJECT OF THE INVENTION

[0014] It is the object of the present invention to provide a solutionto one or more of the above mentioned problems by the provision ofalternative tensio-active products which are suitable as surfactants.

DESCRIPTION OF THE INVENTION

[0015] In their search for alternative and improved surfactants, theinventors have found that certain alkyl urethanes of glucosides providea solution to one or more of said problems.

[0016] In accordance with these findings, the present invention providesthe use as tensio-active agents of alkyl urethanes of glucosides,particularly of alkyl urethanes of starch hydrolysates, provides novelalkyl urethanes of glucosides with tensio-active properties, a methodfor the manufacture of said urethanes, and compositions comprising oneor more of said urethanes as surfactants.

[0017] By tensio-active agent, surface-active agent and surfactant aremeant herein compounds that reduce the surface tension when dissolved inwater or in an aqueous medium, or which reduce interfacial tensionbetween two liquids, between a liquid and a solid or between a liquidand a gas. These terms are used herein interchangeably. The same appliesto the terms which designate said properties.

[0018] By the term alkyl urethane(s), herein in short urethane(s), aredesignated a class of compounds bearing an alkyl-NH—CO—O— group (formedfor example by the reaction of an alkyl isocyanate with an alcoholichydroxyl group bearing substrate), whereas the individual compounds arecommonly named N-alkyl carbamates, i.e. as esters of N-alkyl carbamicacid. However, the terms urethane(s) and carbamate(s) are often, also inthis description, interchanged.

DETAILED DESCRIPTION OF THE INVENTION

[0019] Starch is a well-known carbohydrate that is abundantly present inmany plants as a biodegradable reserve polysaccharide. Starch moleculesare polymers composed of D-glucosyl units which are linked to oneanother by α-1,4 glucosyl-glucosyl bounds thus forming a linear chainstarch structure (termed amylose) or by α-1,4 and α-1,6glucosyl-glucosyl bounds thus forming a branched chain starch structure(termed amylopectin) having a α-1,6 glucosyl-glucosyl bound at thebranching point.

[0020] Starch occurs in nature as a polydisperse mixture of polymericmolecules which have, depending on the plant source, mainly a linearstructure or mainly a branched structure. Starch can also occur innature as a polydisperse mixture of molecules with said structures. Thedegree of polymerisation (DP), i.e. the number of glucosyl units linkedto one another in a starch molecule, may widely vary and it largelydepends on the plant source and the harvesting time.

[0021] The linkages between the glucosyl units are sensitive tohydrolysis, heat and shearing forces. This phenomenon is industriallyexploited to prepare through acidic hydrolysis, enzymatic hydrolysis,thermal treatment or shearing, or through combinations of saidtreatments, various starch derivatives, generically termed herein starchhydrolysates. Depending on the source of the starch, the hydrolysiscatalyst, the hydrolysis conditions, the thermal treatment and/or theshearing conditions, a wide variety of starch hydrolysates can beobtained, ranging from a product essentially composed of glucose, overproducts commonly termed glucose syrups, to products commonly termedmaltodextrins and dextrins. Starch hydrolysates are well known in theart.

[0022] D-glucose (dextrose) presents strong reducing power. Starchhydrolysates are polydisperse mixtures, composed of D-glucose,oligomeric (DP 2≦10) and/or polymeric (DP>10) molecules composed ofD-glucosyl chains, which also present reducing power resulting from thepresence of D-glucose and reducing sugar units (which are essentiallyterminal glucosyl units) on the oligomeric and polymeric molecules.

[0023] A result thereof is that, starting from a given starch product,the more the hydrolysis has proceeded, the more molecules (monomericD-glucose, oligomeric and remaining polymeric molecules) will be presentin the hydrolysate, and thus the higher the reducing powder of theobtained starch hydrolysate. Accordingly, the reducing power of starchhydrolysates has become the distinguishing feature of choice todifferentiate and designate the various starch hydrolysate products. Thereducing power is expressed as dextrose equivalents (D.E.) whichformally corresponds to the grams of D-glucose (dextrose) per 100 gramsof dry substance. D-glucose having per definition a D.E. of 100, theD.E. indicates the amount of D-glucose and reducing sugar units(expressed as dextrose) in a given product on a dry product basis. Thusthe D.E. is in fact also a measurement of the extent of the hydrolysisof the starch and also a relative indication of the average molecularweight of the glucose polymers in the starch hydrolysate.

[0024] The D.E. of starch hydrolysates, apart from hydrolysates composedessentially of D-glucose, may range from 1 to about 96 and starchhydrolysates are commercially available in a wide variety of gradesbased on the D.E.

[0025] Hydrolysates with a D.E. greater than 20 are commonly termedglucose syrups. Glucose syrups with a D.E. up to 47 can be dried byconventional techniques, for example by spray drying, to yield so-called“dried glucose syrups” in powder form, containing maximum about 5 wt %humidity.

[0026] Hydrolysates with a D.E. of 20 or less are commonly termedmaltodextrins and dextrins. The manufacturing process usually involvesat the end a spray drying step, yielding these hydrolysate products inpowder form also containing maximum about 5 wt % humidity (wt %indicates % by weight).

[0027] Glucose syrups, maltodextrins and dextrins are industrially madeat large scale from various starch sources under controlled hydrolysisconditions according to well-known methods. The various grades of starchhydrolysates obtained are usually defined by their starch sourcematerial and by their D.E. value, often in combination with anindication of the method of manufacture (e.g. maltodextrins/dextrins).

[0028] It has to be noted that whereas starch is normally present in theform of spherical particles, maltodextrins and glucose syrups are not.Indeed, in preparation of the hydrolysis reaction leading to saidproducts, the starch particles have been submitted to a treatment whichhas brought them into solution or in the form of a swollen gel. As aresult thereof and in combination with the subsequent hydrolysis of thestarch molecules, said spherical particle form has been definitivelybroken up.

[0029] Although following certain Regulations the term maltodextrins isreserved to products derived from corn starch, the term maltodextrin(s)used herein in not limited to the hydrolysate of corn starch butindicates herein starch hydrolysates with a D.E. of 20 or less obtainedfrom starch from any source.

[0030] Typically commercial sources of starch are corn, potato, tapioca,rice, sorgum and wheat. However the starch hydrolysates which aresuitable according to the present invention are not limited to starchfrom said sources, but they extend to starch from any source.

[0031] Glucose syrups, maltodextrins and dextrins are well known andcommercially available. For example, the production, properties andapplications of glucose syrups and maltodextrins have been described inreview articles in the book Starch Hydrolysis Products, WorldwideTechnology, Production and Applictions, Weinheim VCH Publishers Inc.(1992). Furthermore, in the technical brochure “GLUCIDEX® Brochure8/09.98” from Roquette company, maltodextrins and dried glucose syrupsare described and various grades are offered for sale.

[0032] In one aspect, the present invention relates to a method of useas a tensio-active agent of a glucoside alkyl urethane (I), also namedglucoside N-alkyl carbamate (I), which is composed of units of generalformula (II)

A (O—CO—NH—R)_(s)  (II)

[0033] wherein

[0034] A represents a glucosyl unit of a starch hydrolysate molecule,the starch hydrolysate having a Dextrose Equivalent (D.E.) ranging from1 to 47,

[0035] (O—CO—NH—R) represents an N-alkyl aminocarbonyloxy group, alsocalled an alkyl carbamate group, replacing a hydroxyl group of theglucosyl unit A, and wherein R represents a linear or branched,saturated or unsaturated alkyl group containing from 3 to 22 carbonatoms, and

[0036] s represents the number of alkyl carbamate groups per glucosylunit which number is commonly expressed as degree of substitution (DS),i.e. the average number of substituents per glucosyl unit of theglucoside alkyl urethane (I), with said DS value ranging from about 0.01to about 2.0.

[0037] The number of hydroxyl groups per glucosyl unit of the subjectglucoside molecules which theoretically can be substituted by acarbamate group is for a non-terminal, non-branched glucosyl unitmaximal 3, whereas said number for a terminal and for a non-terminalbranched glucosyl unit is, respectively, 4 and 2. Furthermore, since theDS represents an average number of substituents per glucosyl unit, it isobvious that in a glucoside N-alkyl carbamate (I) molecule there may beglucosyl units present which are not substituted by an alkyl carbamategroup (thus s in formula (II) being zero for said glucosyl unit).

[0038] In an other aspect, the present invention relates to novelglucoside alkyl urethanes (I) composed of units of general formula (II)defined above.

[0039] In a further aspect, the present invention relates to a processfor the manufacture of the glucoside alkyl urethanes (I) composed ofunits of general formula (II) defined above.

[0040] In still a further aspect, the present invention relates to acomposition comprising as tensio-active agent one or more glucosidealkyl urethanes (I) composed of units of general formula (II) definedabove, and to a method for the manufacture of said composition.

[0041] Hereinafter the term glucoside alkyl urethane(s) (I) composed ofunits of general formula (II) according to the present invention isabbreviated to glucoside alkyl urethane(s) (I), urethane(s) (I),glucoside N-alkyl carbamate(s) (I), and carbamate(s) (I), terms whichare used interchangeably.

[0042] Starch hydrolysates commonly appear in the form of a polydispersemixture of glucoside molecules. Accordingly, when such a mixture isused, as is usually the case, as starting material for the preparationof a glucoside alkyl urethane (I), the product obtained is also acorresponding polydisperse mixture of glucoside alkyl urethanes (I).Such polydisperse mixtures of glucoside alkyl urethanes (I) are verysuitable for use as tensio-active agents in accordance with the presentinvention and in fact constitute a preferred embodiment thereof.

[0043] Commercial grades of starch hydrolysates, composed of saidpolydisperse mixture of glucoside molecules and having a D.E. rangingfrom 1 to 47 are very suitable for the preparation of glucoside alkylurethanes (I). On the other hand, mixtures of one or more commercialgrades of starch hydrolysates can also be used as source material in themanufacture of glucoside alkyl urethanes (I). This flexibility in choiceof source material for the preparation of urethanes (I) constitutes asignificant technical advantage. Indeed the physical and tensio-activeproperties of the glucoside alkyl urethanes (I) of the invention partlydepend on the D.E. of the starch hydrolysate used for their preparation.Accordingly, the possibility of using starch hydrolysates or mixtures ofstarch hydrolysates with selected D.E. values enables to control to acertain extent the physical and tensio-active properties of theglucoside alkyl urethanes (I).

[0044] Typically suitable starch hydrolysates for use in the preparationof glucoside N-alkyl urethanes (I) of the invention are for exampleGLUCIDEX® maltodextrins and GLUCIDEX® dried glucose syrups which areavailable from ROQUETTE company, such as the maltodextrins of type 1(potato based with D.E. max 5), type 2 (Waxy Maize based with D.E. max5), type 6 (Waxy Maize based with D.E. 5 to 8), type 9 (Potato basedwith D.E. 8 to 10), and maltodextrins of type 12 (D.E. 11 to 14), type17 (D.E. 15 to 18) and type 19 (D.E. 18 to 20), as well as dried glucosesyrups of type 21 (D.E. 20 to 23), type 28E (D.E. 28 to 31), type 29(D.E. 28 to 31), type 32 (D.E. 31 to 34), type 33 (D.E. 31 to 34), type38 (D.E. 36 to 40), type 39 (D.E. 38 to 41), type 40 (D.E. 38 to 42) andtype 47 (D.E. 43 to 47).

[0045] Depending on the preparation method and the purification/workingup procedure used, starch hydrolysates commonly contain a certaincontent of D-glucose. For example, the D-glucose content of GLUCIDEX®maltodextrins typically ranges from about 0.5% to about 2% (% is % ontotal hydrocarbons), and of GLUCIDEX® dried glucose syrups the D-glucosecontent typically ranges from about 3% to about 17%.

[0046] Accordingly, when starch hydrolysate products containing acertain amount of glucose are transformed into glucoside alkyl urethanes(I), said glucose may simultaneously be transformed into thecorresponding glucose N-alkyl urethane. Depending on the preparationmethod, in particular on the isolation and purification of the urethane(I), the concentration of glucose alkyl urethane in the urethane (I) maycorrespond to the concentration of D-glucose in the starch hydrolysate,but usually, said concentration will be reduced.

[0047] However the presence of glucose N-alkyl carbamate in theglucoside N-alkyl urethanes (I) according to the present invention hasno adverse effect on the properties, particularly on the tensio-activeproperties of the glucoside alkyl urethanes (I) and of compositionscontaining said glucoside alkyl urethanes (I). However, the totalconcentration of glucose N-alkyl carbamate in the urethanes (I) on thetotal amount of alkyl urethanes (I) should be less than 20%, preferablyless than 15%, more preferably less than 10%, even more preferably lessthan 5% and most preferably maximally 3%.

[0048] The alkyl group of the alkyl urethanes (I) of the presentinvention, i.e. the R group in formula (II) defined herein above, ispreferably a saturated C₃-C₂₂ alkyl group, more preferably a saturatedC₄-C₁₈ alkyl group, even more preferably a saturated linear C₄-C₁₈ alkylgroup, most preferably a saturated linear C₆-C₁₈ alkyl group. Typicallysuitable alkyl groups include butyl, hexyl, octyl, decyl, dodecyl,tetradecyl, hexadecyl and octadecyl groups.

[0049] In another preferred embodiment, the alkyl group is amono-unsaturated C₃-C₂₂ alkyl group, preferably a mono-unsaturatedC₄-C₁₈ alkyl group, most preferably a mono-unsaturated linear C₆-C₁₈alkyl group. Typically suitable mono-unsaturated alkyl groups includehexenyl, octenyl, decenyl, dodecenyl, tetradecenyl, hexadecenyl andoctadecenyl groups.

[0050] In the urethane (I) of the invention, all R groups of thecomposing units of formula (II) may be the same, but the urethane (I)may also be composed of units of formula (II) bearing different R groupsas defined herein before. The latter urethanes (I) can be easilyprepared, according to the method described below, by reacting a starchhydrolysate with an isocyanate of formula R-NCO which is in fact amixture of two or more isocyanates bearing different R groups definedabove.

[0051] Saturated alkyl isocyanates can be prepared conventionally, e.g.by reacting a primary or secondary alkyl-amine with phosgene.Unsaturated alkylisocyanates can be prepared similarly fromalkenyl-amines. Alpha-beta unsaturated alkylisocyanates of formulaR²R³C═CH—NCO (III) wherein the radical R²R³C═CH—corresponds to the groupR of formula (II) and wherein R² represents hydrogen or an alkyl groupand R³ represents an alkyl or vinyl group, can be prepared bycondensation of the aldehyde R²R³CH—CHO with Me₃C—NH2, followed byreaction of the resultant Schiff base (in equilibrium with its enamineform) with phosgene, and thermal elimination of Me₃C—Cl as disclosed byK. Koenig et al. (Angew. Chem., 91(4), 334-335 (1979)). Furthermore,various unsaturated alkylisocyanates are disclosed, inter alia in U.S.Pat. No. 3,890,383 and U.S. Pat. No. 3,803,062 of Dow Chemical Co. Manyalkyl cyanates of formula R—N═C═O (R as defined above) are commerciallyavailable.

[0052] The glucoside alkyl urethanes (I) in accordance with the presentinvention have a degree of substitution (DS) ranging from 0.01 to 2.0,preferably from 0.03 to 1.0, more preferably from 0.04 to 0.5.

[0053] The positions on the glucosyl units of the glucoside alkylurethanes (I) where the said alkyl carbamate substituent or substituentsare located, are not critical with respect to the present invention.

[0054] The glucoside alkyl urethanes (I) of the present invention can beprepared in analogy with conventional methods for the preparation ofurethanes of monosaccharides, disaccharides, and polysaccharides, forexample, by reacting the starch hydrolysate with the selected alkylisocyanate or mixture of alkyl isocyanates, in solution in a solventwhich is inert with respect to the starch hydrolysate, the isocyanateand the reaction product. Suitable solvents include solvents or solventmixtures which are free of reactive hydroxyl and amine groups, such asfor example dimethyl formamide (DMF), dimethyl sulfoxide (DMSO) andN-methyl pyrrolidone (NMP).

[0055] The reaction between the starch hydrolysate and thealkylisocyanate has to be carried out, most preferably under anhydrousconditions. In view thereof, the starch hydrolysate as well as thesolvent(s) are dried, preferably to a water content of less than 0.5 wt%, prior to bring them into contact with the alkyl isocyanate. Thedrying can be carried out by conventional techniques, including, forexample by heating the starch hydrolysate in a stream of dry air, or byheating the starch hydrolysate under reduced pressure, or by removingthe water through azeotropic distillation, optionally under reducedpressure, from a solution of the starch hydrolysate in the solventchosen for the reaction. During the drying a maximum temperature,depending on the nature of the starch hydrolysate and the solvent shouldnot be exceeded in order to avoid any decomposition or side reaction.Preferably said temperature should be kept below about 80° C.

[0056] The reaction is typically carried out by bringing the starchhydrolysate dissolved in a suitable solvent into contact, under gentlyto vigorous stirring, with the alkyl isocyanate in neat form or alsodissolved in an anhydrous solvent. The reaction can be carried out overa wide temperature range, typically from room temperature till about 80°C. or the reflux temperature of the reaction mixture if it is lower,preferably at a temperature between about 60° C. and about 80° C.

[0057] Typically, the starch hydrolysate is dissolved in a suitablesolvent, where necessary under heating. Accordingly the alkyl isocyanate(optionally dissolved in the same or in another inert solvent but whichis preferably miscible with the former solvent) is slowly added understirring to the dissolved glucoside. The desired degree of substitutionof the glucoside alkyl urethane (I) can be obtained by controlling theratio of the reactants. Since the reaction of an alkyl isocyanate withan alcoholic hydroxyl group to form an urethane is about a quantitativereaction, the degree of substitution of the urethane (I) can becontrolled by the selection of the proper mole ratio of the alkylisocyanate per glucosyl unit of the starch hydrolysate. Usually thereaction mixture is heated with stirring during a certain time, usuallyfrom about 30 minutes to about 24 hours, in order to complete thereaction between the reagents. The reaction mixture is then worked up byconventional techniques, for example, by precipitating the formedurethane (I) through pouring the reaction mixture, usually after coolingto room temperature, in a precipitant solvent, which is a solvent thatis miscible with the solvent or solvents used to dissolve the reagentsbut in which the glucoside alkyl urethane (I) is not or very poorlysoluble. The urethane (I) is then physically isolated from the reactionmixture, for example by filtration or centrifugation, washed with asuitable solvent in which the urethane (I) is not or only very slightlysoluble, and dried via common techniques.

[0058] A further convenient method to synthesize a desired urethane (I)according to the present invention, occurs in an analogue manner to theone described by W. Gerhardt, Abh. Dtsch. Akad. Wiss. Berlin, KL. Chem.Geol. Biol., Vol 1966(6), 24-36, (1967) (C.A., 68, 14323). It involvesthe transformation in a one-pot reaction in dimethyl formamide of thestarch hydrolysate with potassium cyanate and with a selected alkylhalogenide, preferably an alkyl bromide.

[0059] The inventors have developed a suitable method for themanufacture of glucoside alkyl urethanes (I), from grades of starchhydrolysates which may contain D-glucose to an extent of about 20% byweight while nevertheless ending up with an urethane (I) which containsa significantly smaller amount of the corresponding D-glucose N-alkylcarbamate. According to this process, the starch hydrolysate is reactedin an inert solvent or solvent mixture (termed herein first solvent)with the selected alkyl isocyanate or alkyl isocyanate mixture which isoptionally dissolved in the same or in another inert first solvent.After the reaction is completed, the reaction mixture is cooled to roomtemperature and treated, preferably after prior concentration byevaporation of a part of the first solvent under reduced pressure, witha solvent or solvent mixture (termed herein precipitant solvent) whereinthe first solvent and a considerable amount of D-glucose alkyl carbamateremain in solution, but in which the glucoside alkyl urethanes (I) arenot or only very slightly soluble. Accordingly, the formed glucosidealkyl urethanes (I) precipitate in the precipitant solvent from whichthey can be easily isolated by a conventional physical separationtechnique such as decantation and/or filtration, or centrifugation. Tocomplete the removal of remaining first solvent and to further reducethe amount of possible remaining D-glucose alkyl carbamate, the isolatedreaction product can be triturated and/or washed with the precipitantsolvent or with another suitable precipitant solvent, or othertechniques can be used such as e.g. redissolving and reprecipitation ofthe obtained urethane (I), followed by its isolation and drying.

[0060] Suitable first solvents include, for example, dimethyl formamide,dimethyl sulfoxide and N-methyl pyrrolidone; suitable precipitantsolvents include, for example, ethers such as diethyl ether,dichloromethane, ketones such as acetone, alcohols and esters.

[0061] The glucoside alkyl urethanes (I) are readily soluble at lowconcentration in water at room temperature. In general, the solubilityin water or an aqueous medium of the glucoside alkyl urethanes (I) willdecrease with an increase of the DS and with an increase of the numberof carbon atoms in the R group in formula (II).

[0062] The glucoside alkyl urethanes (I) present good to excellenttensio-active properties, even at very low concentration. Accordingly,they are very useful as surface-active agents because they significantlyreduce interfacial tension between an aqueous liquid and a non-aqueousliquid, between an aqueous liquid and a solid, and between an aqueousliquid and a gas.

[0063] Preferably the glucoside alkyl urethanes (I) are used assurface-active agent in an aqueous medium, more preferably in water, ata concentration ranging from about 0.001% to about 5%, preferably fromabout 0.005% to about 3%, more preferably from about 0.01% to about 2%,even more preferably from about 0.01% to about 1% (concentration in %weight/volume {% w/v}).

[0064] As a non-limiting illustration of the present invention, thepreparation and tensio-active properties of some glucoside alkylurethanes (I) are shown in the Examples and Tables below.

[0065] General procedure used for the manufacture of glucoside alkylurethanes (I). The reaction is carried out in the absence of humiditywith anhydrous reagents and solvents. The glucoside, conventionallydried, e.g. under vacuum over P2O5 or by azeotropically distilling offof the water by means of a suitable solvent, is dissolved, with stirringunder heating to maximally 80° C., in a minimum amount of solvent, e.g.dimethyl formamide (DMF) or N-methyl pyrrolidone (NMP). Preferably themixture is kept between about 60° C. to about 80° C. until all glucosidehas dissolved. Then, at a temperature between about 60° C. to about 80°C., a pre-defined amount (determined in mole equivalents on glucosylunits in the glucoside; for the calculation, the amount of glucosidestarting material is taken as composed of 100% glucosyl units) of aselected alkyl isocyanate, optionally diluted with a suitable solvent,e.g. DMF, is added slowly, preferably dropwise, under vigorous stirringto the glucoside solution and the obtained mixture is stirred at saidtemperature for about 24 hours in total after addition of the alkylisocyanate to complete the reaction. Accordingly, the mixture is cooledto room temperature, optionally part of the solvent is removed byevaporation under reduced pressure, and the mixture is dropwise addedunder vigorous stirring to an excess of precipitant solvent. The formedglucoside alkyl urethane (I) precipitates usually as a white powder oras white lumps. After removal of the supernatant solvent mixture, e.g.by decantation and or filtration, the isolated precipitate, i.e. theglucoside alkyl urethane (I) formed, can be further purified by washingor trituration with a non-solvent, e.g. ether, acetone or methylenechloride, or they may be redissolved and reprecipitated to removepossibly included solvent and impurities, yielding the glucoside alkylurethane (I) in powder or granulate form, which is then isolated anddried. The yields of glycoside alkyl carbamates (I) obtained are goodand the formation of the urethanes (I) has been confirmed byIR-spectroscopy and by ¹³C-NMR spectroscopy.

[0066] The above general procedure is further illustrated by thefollowing examples. The tensio-active properties of the glucoside alkylurethanes (I) were determined by measuring the surface tension at 20° C.of an aqueous solution of the compounds with a tensiometer following theDu Nouy ring method.

EXAMPLE 1 GLUCIDEX® D.E. 2 N-n-octyl carbamate

[0067] 10 g GLUCIDEX® D.E. 2 were dissolved under stirring at about 70°C. in 18 ml of dry DMF. To the solution 0.547 ml n-octyl isocyanate wereadded dropwise with stirring at 70° C. and stirring was continued at 70°C. for 24 hours. After cooling to room temperature, the solution wasadded under stirring to 100 ml dry diethyl ether and the mixture wasstirred for 1 hour. The white precipitate obtained was isolated byfiltration, washed with dichloromethane and dried (by removing residualsolvent under reduced pressure), yielding GLUCIDEX® D.E. 2N-n-octyl-carbamate with a degree of substitution of 0.035-0.05(determined by ¹H NMR-270 MHz).

EXAMPLE 2 GLUCIDEX® D.E. 2 N-n-octyl carbamate

[0068] 10 g GLUCIDEX® D.E. 2 were dissolved under stirring at about 70°C. in 18 ml of dry N-methyl-pyrrolidone (NMP). To the solution 0.547 mln-octyl isocyanate were added dropwise with stirring at 70° C. andstirring was continued at 70° C. for 24 hours. After cooling to roomtemperature, the solution was added under stirring to 100 ml dry acetoneand the mixture was stirred for 1 hour. The white precipitate obtainedwas isolated by filtration, washed with dichloromethane, and dried (theresidual solvent was removed under reduced pressure), yielding GLUCIDEX®D.E. 2 N-n-octyl-carbamate with a degree of substitution of 0.035-0.05(determined by ¹H NMR -270 MHz).

EXAMPLE 3 GLUCIDEX® D.E. 2 N-n-octyl carbamate

[0069] 10 g GLUCIDEX® D.E. 2 were dissolved under stirring at about 70°C. in 18 ml of dry NMP. To the solution 0.547 ml n-octyl isocyanate wereadded dropwise with stirring at 70° C. and stirring was continued at 70°C. for 24 hours. The reaction mixture was cooled to about 45° C. andpulverised through a nozzle at about 3 ml/min into a stream of CO₂ at200 bar. The flow rate of the CO₂ was about 15 kg/hr. The CO₂ being nota solvent for the carbamate (I), the carbamate (I) crystallises in theCO₂ stream while the NMP dissolves in the CO_(2.) At the bottom of thereactor, the formed GLUCIDEX® D.E. 2 N-n-octyl carbamate accumulates asa fine, white powder, while the CO₂ stream liberates after expansion,the NMP in one or more cyclones. The obtained GLUCIDEX® D.E. 2 N-n-octylcarbamate had a degree of substitution of 0.035-0.05 (determined by ¹HNMR-270 MHz).

EXAMPLE 4 GLUCIDEX® D.E. 28 N-n-dodecyl carbamate

[0070] 10 g GLUCIDEX® D.E. 28 were dissolved under stirring at about 70°C. in 14 ml of dry DMF. To the solution 1.49 ml n-dodecyl isocyanatewere added dropwise with stirring at 70° C. and stirring was continuedat 70° C. for 24 hours. After cooling to room temperature, the solutionwas added under stirring to 100 ml dry diethyl ether and the mixture wasstirred for 1 hour. The white precipitate formed was isolated byfiltration, washed with dichloromethane and dried (residual solvent wasremoved under reduced pressure), yielding GLUCIDEX® D.E. 28N-n-dodecyl-carbamate with a degree of substitution of 0.075-0.1(determined by ¹H NMR-270 MHz).

EXAMPLE 5 GLUCIDEX® D.E. 47 N-n-dodecyl carbamate

[0071] 10 g GLUCIDEX® D.E. 47 were dissolved under stirring at about 70°C. in 14 ml of dry DMF. To the solution 1.49 ml n-dodecyl isocyanatewere dropwise added with stirring at 70° C. and stirring was continuedat 70° C. for 24 hours. After cooling to room temperature, the solutionwas added under stirring to 100 ml dry diethyl ether and the mixture wasstirred for 1 hour. The white precipitate formed was isolated byfiltration, treated with dichloromethane and dried (residual solvent wasremoved under reduced pressure), yielding GLUCIDEX® D.E. 47 N-n-dodecylcarbamate with a degree of substitution of 0.085-0.1 (determined by ¹HNMR-270 MHz).

[0072] Following the procedure of examples 1, 2, 4 or 5, severalglucoside N-alkyl carbamates (I) have been prepared which are listed inTable 1 below. TABLE 1 GLUCIDEX ® alkyl carbamates (I) degree degreeProduct substit. substit. Lab Product GLUCIDEX ® type alkyl DS DS codenumber (D.E.) group* (theor)** (NMR)** AM 63 1 GLUCIDEX ® 2 8 0.1 AM 1112 GLUCIDEX ® 2 8 0.2 AM 64 3 GLUCIDEX ® 2 8 0.05 AM 110 4 GLUCIDEX ® 2 80.15 AM 114 5 GLUCIDEX ® 28 8 0.2 AM 65 6 GLUCIDEX ® 28 8 0.05 0.06 AM66 7 GLUCIDEX ® 28 8 0.1 0.12 AM 113 8 GLUCIDEX ® 28 8 0.15 AM 42 9GLUCIDEX ® 28 8 0.2 AM 43 10 GLUCIDEX ® 28 8 0.4 0.42-0.48 AM 112 11GLUCIDEX ® 47 8 0.2 AM 67 12 GLUCIDEX ® 47 8 0.05 0.07 AM 68 13GLUCIDEX ® 47 8 0.1 0.11 AM 46 14 GLUCIDEX ® 47 8 0.2 AM 47 15GLUCIDEX ® 47 8 0.4 0.42 AM 115 16 GLUCIDEX ® 2 12 0.1 AM 142 17GLUCIDEX ® 2 12 0.2 AM 141 18 GLUCIDEX ® 2 12 0.05 AM 116 19 GLUCIDEX ®28 12 0.1 AM 144 20 GLUCIDEX ® 28 12 0.2 0.21 AM 143 21 GLUCIDEX ® 28 120.05 0.058 AM 117 22 GLUCIDEX ® 47 12 0.1 AM 23 GLUCIDEX ® 47 12 0.2146b AM 145 24 GLUCIDEX ® 47 12 0.05 0.042 AM 25 GLUCIDEX ® 47 12 0.20.197 146a AM 139 26 GLUCIDEX ® 2 18 0.1 AM 138 27 GLUCIDEX ® 2 18 0.05AM 137 28 GLUCIDEX ® 28 18 0.1 AM 136 29 GLUCIDEX ® 28 18 0.05 0.047 AM134 30 GLUCIDEX ® 47 18 0.05 0.051 AM 135 31 GLUCIDEX ® 47 18 0.1 0.086

[0073] Surface Tension and Interface Tension of Carbamates (I)

[0074] The surface tension as well as the interfacial tension have beendetermined for carbamates (I) according to the “Du Nouy ring method” bymeans of a Krüss tensiometer. The results are given in Table 2 below.The product number corresponds to the product number given in Table 1above. TABLE 2 Surface tension and interfacial tension Surfactant:carbamate (I) Interfacial Tension°° Conc. in % w/v Surface Tension° at20° C. Product in surfactant at 20° C. (mN/m) No (water) solution (mN/m)paraffinic oil* 19 0.01 36.5 5.7 22 0.01 37.4 6.3 1 0.01 28.2 1.7 7 0.0140 11

[0075] The experimental data shown in Table 2 clearly indicate that theurethanes (I) present useful to excellent tensio-active properties atlow concentration e.g. a concentration of 0.01% w/v in water, and fromsaid data it can be concluded that the urethanes (I) have greatpotential as surfactants.

[0076] Emulsifying Properties of Carbamates (I)

[0077] The carbamates (I) present very good emulsifying properties, inparticular with respect to oil/water systems. Typical oils include, forexample, vegetable oils, hydrocarbon oils and mineral oils, and anymixture thereof. The emulsions may find wide applications, depending ofthe nature of the oil, in various fields, such as, for example, inhousehold products, in person care applications, in agro-chemicals, inpesticides and in industrially used emulsions.

[0078] The oil content in the emulsions can, for example, range fromabout 5 wt % to about 75 wt %. The total concentration of thesurfactant, carbamate (I) or a mixture of two or more carbamates (I), inthe surfactant solution used to build the water phase can, for example,range from about 0.3 wt % to about 3 wt %, typically from about 0.5 wt %to about 2 wt %. The emulsifying properties of the urethanes (I) areillustrated by the example below in which various oil/water emulsions,containing a carbamates (I) as surfactant, were prepared and evaluatedaccording to standard procedures.

[0079] Preparation of the Emulsions.

[0080] To 25 ml surfactant solution, composed of a given concentration(wt %) of a carbamates (I) in demineralised water, were added dropwise25 ml oil, while the mixture was stirred by means of an Ultra-Turrax*(CAT X620) (*trade name). The oil was added during the first step of afour step mixing process, in which the mixing speed was stepwiseincreased as indicated in Table 3 below, yielding the emulsion. However,the mixing procedure is not critical since other procedures than the onegiven yield about the same results. TABLE 3 Mixing procedure Step 1 2 34 Stirring speed (rpm) 9,500 13,500 20,500 24,000 Stirring time (sec)120 60 45 60

[0081] Evaluation of the Emulsions.

[0082] The evolution in time of the emulsions kept at room temperaturewas followed both microscopically (evolution of the droplet size) andmacroscopically (visual check for oil separation). The results are shownin Table 4 below. TABLE 4 Evaluation of oil/water emulsions containingcarbamates (I) Total wt % of carbamate (I) in the surfactant AlkylStability of solution carbamate (I) the emulsion (= water phase) ProductNo* Oil (days) (2) 1 3 isoparaffinic oil (1) >70 2 3 isoparaffinic oil(1) >70 1 1 isoparaffinic oil (1) >70 2 1 isoparaffinic oil (1) >70 2 18isoparaffinic oil (1) >14 4 18 isoparaffinic oil (1) >14 2 17isoparaffinic oil (1) >14 4 17 isoparaffinic oil (1) >14 2 20isoparaffinic oil (1) >14 4 20 isoparaffinic oil (1) >14 4 25isoparaffinic oil (1) >14 2 27 isoparaffinic oil (1) >14 4 27isoparaffinic oil (1) >14 4 29 isoparaffinic oil (1) >14 4 30isoparaffinic oil (1) >14 2 26 isoparaffinic oil (1) >14 4 26isoparaffinic oil (1) >14 2 31 isoparaffinic oil (1) >14 4 31isoparaffinic oil (1) >14

[0083] Use of Glucoside Alkyl Carbamates (I) as Dispersants

[0084] Dispersions were made from surfactant solutions containing one ormore carbamates (I) described above by adding a pre-determined amount ofa product in powder form to said surfactant solution under stirring bymeans of an Ultra-Turrax* (CAT X 620) (*trade name). The powder wasadded during the first step of a four step mixing process in which themixing speed was increase stepwise. However, the mixing procedure is notcritical since also other procedures yield about the same results. Thedispersions obtained were inspected visually and microscopically (100×)in function of the time.

[0085] A dispersion was made (mixing procedure 90 sec. at 9,500 rpm; 60sec. at 13,500 rpm; 30 sec. at 20,500 rpm and 15 sec. at 24,000 rpm) of0.5 g carbon black (Efltex 575 variant, Cabot Corporation) in 25 mlsurfactant solution of 3% w/v of respectively carbamate No. 1, 3 and 19.For all three carbamates (I) dispersions with a very good stability wereobtained in which the particle size of the dispersed product was smallerthan in a corresponding dispersion similarly made from water (withoutany surfactant) and the powder product.

[0086] Similarly a dispersion was made (mixing procedure 240 sec. at8,000 rpm) of 7.5 g Al₂O₃ of ALCOA in) in 25 ml surfactant solution of3% w/v of respectively carbamate No. 3, 16 and 19. For all threecarbamates (I) dispersions with a very good stability were obtained inwhich the particle size of the dispersed product was smaller than in acorresponding dispersion similarly made from water (without anysurfactant) and the powder product.

[0087] The above indicates that alkylcarbamates (I) have great potentialas dispersants, for hydrophobic and hydrophylic products, since theyenable to prepare dispersions with good stability.

[0088] The above indicated properties of the glucoside alkyl carbamates(I) are highly valuable for use as surface-active agents in variouscompositions and in premixes for the preparation of said compositions.These compositions and premixes can be prepared according toconventional techniques, for example, by simple mixing, preferably underlow speed stirring, of all ingredients of the composition in therequired amounts, including the selected one or more glucoside glucosidealkyl urethanes (I), or by addition of a desired amount of the one ormore selected glucoside alkyl urethanes (I) to a pre-mix of all otheringredients, or by adding a pre-mix containing all required ingredients,including the selected one or more glucoside alkyl urethanes (I), to amedium such as water, an aqueous or a non-aqueous liquid, for example anoil, or a pasty composition.

[0089] The surface-active agents of the present invention are suitablefor use as detergents, emulsifiers, emulsion stabilisers, liposomestabilisers, foaming agents, foam stabilisers and/or wetting agents invarious household and industrial applications, such as for example indetergents for laundry washing, detergents for dish washing, industrialdetergents, emulsifiers in cosmetics, emulsifiers and stabilisers ininks, in paintings and in coating compositions, and foaming agentsand/or foam stabilisers in shampoo's.

[0090] Furthermore, the glucoside alkyl urethanes (I) present goodthermal and chemical stability in combination with good biodegradabilityand they are free of phosphor/phosphates. Furthermore, the main rawmaterial for the manufacture of the carbamates (I), i.e. the starchhydrolysates, are common agro-chemicals, i.e. carbohydrates from vegetalorigin which in fact constitute renewable resources.

[0091] The combination of said features and taking into account the goodbiodegradability of the glucoside alkyl carbamates (I) makes that thecarbamates (I) are environmentally well acceptable. Besides, starchhydrolysates are available at industrial scale in suitable quality andat acceptable raw material prices which is an economically veryimportant feature, making the use of the urethanes (I) as surfactants atindustrial scale possible and attractive.

1. Use as a tensio-active agent of a glucoside alkyl urethane (I), whichis composed of units of general formula (II) A (O—CO—NH—R)_(s)  (II)wherein A represents a glucosyl unit of a starch hydrolysate molecule,the starch hydrolysate having a Dextrose Equivalent (D.E.) ranging from1 to 47, (O—CO—NH—R) represents an N-alkyl aminocarbonyloxy groupreplacing a hydroxyl group of the glucosyl unit A, and wherein Rrepresents a linear or branched, saturated or unsaturated alkyl groupcontaining from 3 to 22 carbon atoms, and s represents the number ofalkyl carbamate groups per glucosyl unit which number is expressed asdegree of substitution (DS) with said DS value ranging from about 0.01to about 2.0.
 2. Use according to claim 1 of an urethane (I) wherein thealkyl group R is a saturated C₃-C₂₂ alkyl group or a mono-unsaturatedC₃-C₂₂ alkyl group.
 3. Use according to any one of claims 1 to 2 of anurethane (I) wherein the alkyl group R is a linear saturated ormono-unsaturated C₆-C₁₈ alkyl group.
 4. Use according to any of claims 1to 3 wherein the urethane (I) is composed of units of formula (II) withtwo or more different alkyl groups R.
 5. Use according to any one ofclaims 1 to 4 of an urethane (I) wherein the degree of substitution(DS), has a value ranging from 0.01 to 0.5.
 6. Use according to any oneof claims 1 to 5 of an urethane (I) wherein the glucoside is amaltodextrin moiety.
 7. Use according to any one of claims 1 to 5 of anurethane (I) wherein the glucoside is dried glucose syrup moiety.
 8. Useas a detergent, emulsifier, emulsion stabiliser, foaming agent, foamstabiliser, liposome stabiliser, dispersant and/or wetting agent of aglucoside alkyl urethane (I) as defined in any one of claims 1 to
 7. 9.Glucoside alkyl urethane (I) which is composed of units of generalformula (II) A (O—CO—NH—R)_(s)  (II) wherein A represents a glucosylunit of a starch hydrolysate molecule, the starch hydrolysate having aDextrose Equivalent (D.E.) ranging from 1 to 47, (O—CO—NH—R) representsan N-alkyl aminocarbonyloxy group replacing a hydroxyl group of theglucosyl unit A, and wherein R represents a linear or branched,saturated or unsaturated alkyl group containing from 3 to 22 carbonatoms, and s represents the number of alkyl carbamate groups perglucosyl unit which number is expressed as degree of substitution (DS)with said DS value ranging from about 0.01 to about 2.0.
 10. Glucosidealkyl urethane (I) according to claim 9 as defined in any one of claims2 to
 8. 11. Composition comprising as surface-active agent one or moreglucoside alkyl urethanes (I) as defined in claim 9 or claim
 10. 12.Composition according to claim 11 wherein the one or more glucosidealkyl urethanes (I) are present in a total concentration of 0.001% to 5%(% w/v).
 13. Composition according to claim 11 which is a pre-mixcomposition suitable for the manufacture, by dilution with water, anaqueous medium or a non-aqueous medium, of a composition as defined inclaim
 12. 14. Process for the manufacture of a glucoside alkyl urethane(I) as defined in claim 9, comprising reacting a starch hydrolysate witha D.E. between 1 and 47, dissolved in a first solvent, with such anamount of alkyl isocyanate that an urethane (I) is yielded having adegree of substitution (DS) ranging from 0.01 to 2.0, the first solventbeing inert with respect to the glucoside, the isocyanate and theurethane (I), followed (i) by precipitation of the formed urethane (I),optionally after partial removal of the first solvent by evaporationunder reduced pressure, either by addition under stirring of aprecipitant solvent to the reaction mixture or by slowly pouring understirring the, optionally concentrated, reaction mixture into aprecipitant solvent, followed by isolation of the precipitated urethane(I), treating or washing of the urethane (I) with a precipitant solvent,and drying of the obtained urethane (I), or (ii) by spraying thereaction mixture in a stream of CO₂ under about 200 bar, with subsequentisolation, optionally washing with a precipitant solvent, and drying ofthe obtained urethane (I).